1. Field of the Invention
The present invention relates to an optical module providing a multi-layered ceramic package.
2. Related Prior Art
Conventional and typical optical module installs a semiconductor laser diode (hereafter denoted as LD) as a source of signal light and a lens to couple the signal light with an external fiber. Some optical modules provide a function to control a temperature of the LD to secure the quality of the signal light. In such an optical module with the temperature control function, a thermo-electric controller (hereafter denoted as TEC) is installed in the package to mount the LD thereon and the signal light to be extracted by being bent the optical axis thereof by, for instance, a mirror.
Recently, in addition to two primary arrangements of, what is called, a co-axial type and a butterfly type, an optical module with the third configuration has been proposed as disclosed in the U.S. Pat. No. 7,476,040, in which the module as a multi-layered ceramic package and optical coupling members are attached to the lid (ceiling) of the package. In such an optical module, an inner space where electrical and optical components are to be installed therein is severely restricted compared to those of conventional arrangements. The position of the lens, that of the optical filter or the mirror, that of a monitoring photodiode (hereafter denoted as MPD) to detect a portion of the signal light emitted from the LD, and so on are necessary to be carefully designed in connection with the position of the LD. The design of the practical module with such a new arrangement is also consistent with a cost including the productivity thereof. The present invention is to provide a new arrangement of an optical module with the multi-layered ceramic package and the TEC installed therein.